The present invention relates to the coating of film strips and, more particularly, to an apparatus and method for applying a protective coating, such as an ultraviolet curable protective coating, to one or both surfaces of a film strip, such as a photographic film strip.
Certain types of film, such as photographic film, are highly susceptible to damage from abrasive contact (e.g. scratching) and from contact with solvents or other liquid materials. As a result, protective coatings have been developed to protect such films from abrasive damage and from solvent contact. In addition, protective coatings may also reduce static electricity which attracts dust and dirt to the film, make fingerprints easy to wipe off, and otherwise protect and preserve the film. The most widely known and commonly used protective coatings are those which are curable by exposure to ultraviolet light, such as those described in U.S. Pat. No. 4,100,134 to Robins et al, U.S. Pat. No. 4,156,046 to Lien et al, U.S. Pat. No. 4,293,606 to Zollinger et al, and U.S. Pat. No. 4,497,861 to Kistner.
Conventional means for applying protective coatings to film strips involve high-speed devices which are both complex and expensive. An example of such a conventional coating device is described in U.S. Pat. No. 4,612,875 to Keable, which discloses a photographic film coater for applying an ultraviolet curable coating material to the opposite sides of roll film by a double-sided coater. Prior to coating, a group of film strips are usually spliced in end-to-end relation by paper splices and formed into a continuous reel. Film from the reel is drawn into a festoon section where it passes in serpentine fashion over a series of rollers until it reaches the double-sided coater. The double-sided coater includes a pair of coaters, each of which in turn includes a pickup roll and an applicator roll. Each pickup roll is partially immersed in a bath of liquid coating material and is positioned in close relation to the applicator roll such that, upon rotation of the pickup roll, the liquid material is transferred from the pickup roll to the applicator roll. Each of the pair of applicator rolls contact opposite sides of the film to transfer a coating of liquid material thereto. After the double-sided coater, the film is contacted by a series of smoothing bars to smooth the liquid coating, and then passes into an ultraviolet curing chamber to cure the liquid material. The film next moves to a film receiving chamber, then to a second festoon, and finally to a take-up reel.
While such complex, high-speed film coating devices are well suited for large commercial operations, they are prohibitively expensive and cumbersome for small operations in which single strips of film are coated on an infrequent basis depending upon individual customer demand. Due to the long and convoluted film path through the conventional coating devices, individual film strips must be spliced together to form a large, continuous reel before the film strips can be coated. As a result, an individual customer otherwise desiring immediate coating of a film strip must wait until a sufficient number of film strips are collected to form a suitably sized reel. In addition, conventional coating devices are somewhat sophisticated and require a fair amount of training in order to operate them.
Accordingly, a need exists in the art for a coating method and apparatus which are relatively inexpensive, easy to operate, and capable of quickly applying a protective coating to an individual film strip on short notice (e.g. while a customer waits). Such method and apparatus would facilitate small operations designed to provide protective coatings to individual photographic film strips immediately after being requested to do so by a consumer.